Cargo lock for fixing cargo pallets to seat tracks in aircraft

ABSTRACT

A cargo locking device for locking of freight in a vehicle such as the stowage of containers or pallets in aircraft in which track connectors, namely the tensile studs are arranged in such a manner that tensile load is distributed between the floor beams. The cargo lock has a lock length about equal to or exceeding the transverse beam pitch, the tensile studs being placed in groups at both ends of the lock and the pawls in the middle of the lock such that pawl loads are split between the forward and the aft stud.

RELATED APPLICATION

This application is a divisional of application Ser. No. 09/120,552filed Jul. 22, 1998, now U.S. Pat. No. 6,193,453, which claims priorityto provisional application Serial No. 60/053,643 filed Jul. 24, 1997.

BACKGROUND OF THE INVENTION

The field of the present invention relates to a cargo lock device thatholds cargo pallets in place within vehicles such as aircraft. Theaircraft includes seat or cargo tracks located in the cargo floor. Theseat tracks are located in the cargo floor and run lengthwise throughthe aircraft. The seat tracks are supported at regular intervalstypically by transverse floor beams. Typically, the cargo lock deviceincludes hooks referred to as pawls and a number of support rollers. Thedevice is connected to a seat track by means of tensile studs and shearties. The studs restrain the lock against vertical motion and the shearties restrain the lock against horizontal motion.

The present inventor has recognized that these cargo locks arestructurally inefficient for the aircraft floor because of theirgeometry and the locations of their studs, shear ties and rollersrelative to the pawls. With the lock in an unfavorable position in theseat track relative to the transverse floor beams, most of the loadapplied by the cargo pallet will transfer through just one floor beam.This situation occurs when the stud that is closest to the pawls islocated directly over top of a floor beam. For example, U.S. Pat. No.5,433,564 discloses a device which employs a resiliently deformablesection in its floor hooks, but does not disclose relative distributionof tensile forces relative to floor support points.

The existing lock designs may minimize cost and weight of the locksthemselves, but these cost and weight savings are disadvantageouslyoffset by the additional structure required in the transverse floorbeams and the seat tracks.

SUMMARY OF THE INVENTION

The present invention is directed to an improved cargo locking devicefor locking of freight in a vehicle such as the stowage of containers,or pallets in aircraft. The improved cargo locking device avoids theaforementioned disadvantages by arranging track connectors, e.g. thetensile studs, in such a manner that tensile load is distributed betweenthe floor beams.

In its preferred embodiment, the cargo lock has a lock length aboutequal to or exceeding the transverse beam pitch. The tensile studs willbe placed in groups at both ends of the lock. The pawls will be placedin the middle of the lock. This arrangement will split the pawl loads(from the cargo pallet) between the forward and the aft stud. Theseparation of the studs is such that the combined loading from the twogroups of studs into a single transverse floor beam never exceeds about50% of the pawl load. The invention will now be described further asillustrated on the attached drawings of examples of its preferredembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cargo lock according to a preferredembodiment of the present invention.

FIG. 2 is a top plan view of the cargo lock of FIG. 1.

FIG. 3 is a side view of the cargo lock of FIG. 1.

FIG. 4 is a side view of a cargo lock similar to the cargo lock in FIG.1 and further including a cross section of the transverse floor beamsand supporting seat track.

FIG. 5 is a front view of the cargo lock in the seat track of FIG. 4.

FIG. 6 is a top view of a tensile stud and a shear tie in a seat track.

FIG. 7 is a side view of an alternate embodiment of the cargo lock alsoof similar configuration to the cargo lock of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will now be describedwith reference to the drawings. To facilitate description, anyidentifying numeral representing an element in one figure will representthe same element in any other figure.

FIGS. 1-3 illustrate a cargo lock 70 having a configuration which isgenerally applicable to the details in the cargo lock 70 a embodiment ofFIGS. 4-6 or the cargo lock 70 b embodiment of FIG. 7.

Referring to FIGS. 1-6, the cargo lock 70/70 a is connected to the seattrack 40 arranged in the floor of the aircraft, the floor 50 beingsupported by beams 51, 52. The cargo lock 70/70 a comprises a frame orbaseplate 10, a pair of pawls 31 and 32, shear ties 21 and 22, and trackconnectors, shown as tensile studs 11 and 12. The pawls 31 and 32 arelocated in the center of the cargo lock 70/70 a. The pawls 31, 32 have acurved or hook portion which secure cargo pallets 33 and 34 to the cargolock 70/70 a. For the purposes of this description, a pawl may compriseany suitable connector which secures the cargo pallet to the cargo lock.The shear ties 21 and 22 fit in scalloped holes 41 in the seat track 40to prevent horizontal movement of the cargo lock 70/70 a.

Details of the tensile studs 11, 12 are best shown in FIG. 5. The stud11 is in the shape of an inverted “T” formed with a flange portion 11 aand a leg portion 11 b. Typically, the leg portion 11 b may have threads11 c at the end for attachment to the baseplate 10 either directly orvia a nut or other suitable connection mechanism.

The tensile studs 11 and 12 are inserted into the seat tracks 40 throughthe scalloped holes 41 and subsequently moved to a position in-betweenthe holes 41 by sliding a short distance p along the length of the seattrack 40 (before the shear ties 21 and 22 are inserted). In thisposition, the circular flange 11 a of each stud 11 is locked below theseat track inner flange 42. The lock 70/70 a is secured in this positionby inserting shear ties 21 and 22. Thus secured in seat track 40, thelock 70/70 a is held in position both vertically and horizontally.

The tensile stud 11 is located at one side of the pawls 31 and 32 onbaseplate 10 and tensile stud 12 at the other side of the pawls 31 and32 on baseplate 10. The distance between the two tensile studs is d. Thepawls 31 and 32 are centrally located near the middle of the distance d.The transverse floor beams 51 and 52 support the seat track 40 at aninterval b. The cargo lock is designed with a distance d preferablyselected to be as close to b as possible, with the maximum benefitrealized as d is equal to b or as d exceeds b.

The cargo lock 70/70 a includes a plurality of rollers 35, 36, 37 and 38secured to the baseplate 10. The rollers 35-38 extend outward from thebottom of the frame 10 and serve to allow the cargo pallets to rollalong the cargo locks thereby facilitating movement of pallets 33 and 34during loading and unloading. Outer rollers 35, 38 are located at theextremities of baseplate 10. The purpose of these outer rollers 35, 38is to ensure that the pallets edge does not become blocked against theedge of the baseplate 10. Inner rollers 36, 37 are located close topawls 31 and 32 within a distance e. The purpose of locating innerrollers 36, 37 close to the pawls 31, 32 is to distribute a load from asingle container in the downward direction over as much as possible thefull length of the baseplate 10. Without these inner rollers, this download would be concentrated at an extremity of baseplate 10 on eitherroller 35 or roller 38.

FIG. 7 illustrates an alternative embodiment for a cargo lock in whichthe same reference numerals have been used as in FIGS. 1 through 6 toindicate corresponding parts. In the embodiment of FIG. 7, the number oftensile studs has been increased to two per side resulting in studs 11and 13, the first track connector, on one side and studs 12 and 14, thesecond track connector, on the other side, which is the same number ofstuds as illustrated in FIGS. 1-3. The centroid 71 of the group oftensile studs 11 and 13 is the location of the effective working axis offorce when both tensile studs are equally loaded with a vertical force(for groups comprising of two tensile studs the centroid is located halfway between tensile studs). Similarly, the centroid 72 of the group oftensile studs 12 and 14 is located in between these studs. The distancebetween the centroids 71 and 72 of the two groups of tensile studs nowdefines d′. The pawls 31 and 32 continue to be located near the middleof the distance d′. One advantage of the alternative embodiment is thatthe load per tensile stud is reduced. In addition, the baseplate 10 andthe seat track 40 are fixed together at the stud groups more securely.This arrangement may have several additional beneficial effects,including but not limited to: 1) preventing the potential rolling overof the top flanges 53 and 54 of the transverse floor beams 51 and 52when the stud groups are located offset from the beams as shown; and 2)reducing maximum bending moment in baseplate 10 which occurs near thepawls 31 and 32.

In use, the tensile studs secure the cargo locks to the tracks in theevent of a downward acceleration of the vehicle resulting in largetensile forces being applied to the lock. The tensile force istransmitted from the pawls 31, 32, through the baseplate 10, and to thestuds 11, 12. The studs then transmit the upward force to the track 40which in turn transmit the forces to the floor and support beams 51, 52.The distance d is defined as the length of the effective separation ofthe tensile attachment points of the cargo lock 70 a to the tracks. Inthe cargo lock 70 a of FIG. 4, the tensile attachment points are locatedat the center of the tensile studs 11 and the center of tensile stud 12.The tensile studs 11, 12 are intentionally positioned at the outer endsof the cargo lock 70 a so as to provide desired separation between theattachment points. Where additional tensile studs are provided such asin cargo lock 70 b of FIG. 7, the attachment points (i.e. the centroidof attachment) are between the stud pairs, namely centroid 71 betweenstud pair 11, 13 and centroid 72 between stud pair 12, 14. The studpairs of cargo lock 70 b are still separated by a distance d′ providingthe desired effective separation between the attachment points.

If additional studs are included along the length of the cargo lock (forexample studs 16, 17, 18, 19 shown in FIG. 4 in phantom) such studs arepreferably designed in conjunction with the flexibility of the tracksand aircraft floor so as not to negate the force separation quality ofthe primary attachment points at the outer ends of the cargo lock. Suchflexibility may be accomplished by including additional vertical spacingor elastomeric connection in the center studs 16-19 such that eventhough the upward tensile force is applied at the center of the cargolock by the pawls 31, 32, the majority of the upward tensile force istransferred to the primary end studs 11, 12 and thereby distributedbetween the support beams 51, 52.

In a preferred construction, the cargo lock is elongated a having arelatively low aspect ratio r defined as the ratio of the height h (i.e.a maximum height of the lock as measured with the pawls 31, 32retracted) to the length d (the effective distance between the endattachment points):

r=h / d.

Preferably, the aspect ratio of an elongated cargo lock is less thanabout ⅛th (0.125) or even smaller, namely about 0.10, with certainimplementations being about 0.06. The aspect ratio h/d of the cargo lock70 a of FIG. 4 and the aspect ratio h/d′ of the cargo lock 70 b of FIG.7 are about 0.05. In a Boeing 727 aircraft, the distance b between thesupport columns is about 20 inches. In actual construction, thedimensions of a cargo lock 70 b for this Boeing 727 aircraft may be

 h=1.15 in

d=20 in

r=0.06

In smaller aircraft, the distance between support beams will be smaller,but the size of the cargo locks will also be smaller but would bedesigned such that d≧b and having an aspect ratio r less than 0.125 toprovided the desired spacing of attachment points.

In a preferred configuration, the cargo lock comprises

a baseplate with a lengthwise orientation over a seat track;

one or more pawls to secure cargo pallets to the lock mounted on thebaseplate;

a tensile stud set (of one or more tensile studs) mounted on thebaseplate on each side of the pawl(s), the stud set being spaced fromthe pawl(s) at a distance that is about half the spacing of the seattrack support points;

shear ties mounted on the baseplate;

rollers mounted to the baseplate on opposite sides of the pawl(s).

Preferably, the distance between the pawl(s) and the tensile studs islarger than half the spacing of the seat track support points. Thedistance may be somewhat smaller, but if the distance is too small, thepreferred weight distribution advantages may be lost.

The rollers are preferably located a distance e (see FIG. 3) away fromthe pawl(s) where e is about less than one-fifth the spacing of the seattrack support points.

In another preferred configuration, a single stud is used on each sideof the pawls.

In another preferred configuration, a pair of tensile studs are disposedon each side of the pawls, the studs of the pair being separated byabout one seat track hole distance (2 p).

In another preferred embodiment, a shear tie is located in-between thetwo tensile studs in a group.

In another preferred embodiment, a single stud is replaced with a groupof two or more tensile studs in any arrangement for which the distancebetween the pawl(s) and the closest tensile stud is about equal to halfthe distance between the seat track support points.

In another preferred embodiment, a cargo lock may include additionalrollers to further distribute the compressive load across the floor. Thecargo locks 70 a/70 b of FIGS. 4 and 7 have four rollers 35-38. A cargolock may include for example six rollers as the lock 70 in FIGS. 1-3,which has a roller 39 a mounted to the baseplate 10 between rollers 35and 36 and another roller 39 b mounted between rollers 37 and 38 at theother end of the baseplate 10. The cargo lock may be provided with anynumber of additional rollers. The rollers are preferable separated asmuch as possible to distribute the loads. In the embodiment of FIGS.1-3, the center rollers 36, 37 are located adjacent the pawls 31, 32.The rollers 36, 37 are shown so close to the pawls 31, 32 that the pawls31, 32 or the rollers 36, 37 may require movable connections (not shown)to the baseplate 10 in order to accommodate retraction of the pawls 31,32.

Though the present invention has been set forth in the form of itspreferred embodiments, it is nevertheless intended that modifications tothe disclosed embodiments may be made without departing from inventiveconcepts set forth herein. The invention, therefore, is not to berestricted except in the spirit of the claims that follow.

What is claimed is:
 1. A system for securing a pallet to tracks in avehicle having transverse support beams spaced by a given spacing,comprising: a cargo lock for securing the pallet to a track, the cargolock having (a) a pawl for engaging the pallet and (b) first and secondtrack connectors for securing the cargo lock to the track, wherein thepawl is centrally positioned on the cargo lock and wherein the first andsecond track connectors are mounted on opposite ends of the cargo lock;wherein length of the cargo lock and spacing of the first and secondtrack connectors from the pawl are selected such that total tensile loadapplied through the pawl is distributed to ensure that individualtensile load applied to any transverse support beam does not exceedabout 50% of the total tensile load applied through the pawl.
 2. Asystem according to claim 1 wherein the first track connector comprisesa pair of closely spaced tensile studs.
 3. A system according to claim 2wherein the cargo lock includes a shear tie located in-between thetensile studs.
 4. A system according to claim 2 wherein the second trackconnector comprises a pair of closely spaced tensile studs.
 5. A systemaccording to claim 1 wherein the first track connector comprises asingle tensile stud.
 6. A system according to claim 1 wherein the firstand second track connectors are evenly spaced from the pawl.
 7. A systemaccording to claim 1 wherein the cargo lock includes at least first andsecond rollers for supporting the pallet, the first and second rollersbeing disposed on opposite sides of the pawl.
 8. A system according toclaim 1 wherein the cargo lock includes a second pawl.
 9. A system forsecuring a pallet to tracks in a vehicle having transverse support beamsspaced by a given spacing, comprising: a cargo lock for securing thepallet to a track, the cargo lock having (a) at least a first pawl forengaging the pallet and (b) first and second track connectors forsecuring the cargo lock to the track, wherein the pawl is generallycentrally positioned on the cargo lock and wherein the first and secondtrack connectors are mounted on opposite ends of the cargo lock; whereinthe cargo lock is constructed and arranged with spacing of the first andsecond track connectors from the pawl and with a length such that totaltensile load applied through the pawl is distributed to ensure thatindividual tensile load applied to any transverse support beam does notexceed about 50% of the total tensile load applied through the pawl. 10.A system according to claim 9 wherein the first track connectorcomprises a pair of closely spaced tensile studs.
 11. A system accordingto claim 10 wherein the cargo lock includes a shear tie locatedin-between the tensile studs.
 12. A system according to claim 9 whereinthe second track connector comprises a pair of closely spaced tensilestuds.
 13. A system according to claim 9 wherein the first trackconnector comprises a single tensile stud.
 14. A system according toclaim 9 wherein the first and second track connectors are evenly spacedfrom the pawl.
 15. A system according to claim 9 wherein the cargo lockincludes at least first and second rollers for supporting the pallet,the first and second rollers being disposed on opposite sides of thepawl.
 16. A system according to claim 1 wherein the cargo lock includesa second pawl disposed adjacent the first pawl.
 17. A system securing apallet to tracks in a vehicle having transverse support beams spaced bya given spacing, comprising: a cargo lock for securing the pallet to atrack, the cargo lock having (a) a pawl for securing the pallet and (b)first and second track connectors for securing the cargo lock to thetrack, wherein the pawl is centrally positioned on the cargo lock andwherein the first and second track connectors are disposed on oppositeends of the cargo lock; means for distributing total tensile loadapplied through the pawl such that an individual tensile load applied toany transverse support beam does not exceed about 50% of the totaltensile load applied through the pawl.
 18. A method of securing a palletto tracks in a vehicle having transverse support beams spaced by a givenspacing, comprising the steps of: installing a cargo lock to a singletrack, the cargo lock having (a) a pawl for engaging the pallet and (b)first and second track connectors for securing the cargo lock to thetrack; centrally positioning the pawl on the cargo lock; mounting thefirst and second track connectors on opposite ends of the cargo lock;selecting length of the cargo lock and spacing the first and secondtrack connectors from the pawl such that total tensile load appliedthrough the pawl is distributed such that individual tensile loadapplied to any transverse support beam does not exceed about 50% of thetotal tensile load applied through the pawl.
 19. A method according toclaim 18 further comprising spacing the track connectors from the pawlat a distance that is at least about half the spacing of the supportbeams.